I have tried plenty of lemon tarts and this one is the absolute best. I like my tart's "tart" so this one definitely has some kick. The pastry is also a favourite and I use it for all sorts of pie recipes.
Combine flour, cornstarch, sugar, and salt by pulsing in a food processor or stirring in a large bowl.
Add cubed butter and process or use a pastry blender to cut in until crumbly. With the motor running add ice water and process just until it comes together. Alternately, drizzle flour mixture with water and stir with a fork until it becomes a ragged dough. Bring together and shape into a disk.
Wrap dough in plastic wrap and refrigerate for 15 minutes.
Press into a 9-inch (23 cm) flan pan, and refrigerate for 15 minutes.
Prick all over with a fork, line with foil, then fill with dried beans or pie weights.
Bake for 20 minutes at 400 degrees, remove paper and beans, prick if puffed and bake 5 minutes longer or until lightly golden. Do not overbake. Remove from oven.
Reduce oven to 350F (180C).
Whisk eggs until creamy. Add sugar and flour and whisk until smooth. Gradually whisk in lemon and lime juices, then lemon peel.
Pour into baked pie shell, place pan on a shallow rimmed baking sheet and bake for 20 minutes or until filling is slightly puffed and barely set (may still wobble slightly in centre). Cool completely.